%0 Journal Article
%J Climate Research
%D 2009
%T Changes and patterns in biologically relevant temperatures in Europe 1941-2000
%A Timothy H. Sparks
%A Aasa, A.
%A Huber, K.
%A Wadsworth, R.
%K climate change
%K growing season
%K phenology
%K spring
%K temperature
%K variation
%X We took daily near-surface air temperature data from across Europe to calculate a series of 12 biologically relevant temperature summaries. Mean values for two 30 yr periods, 1941–1970 and 1971–2000, were compared and rates of change calculated for those meteorological stations with sufficient data. We generated contour maps for these temperature summaries for both 30 yr periods and for the difference between them; we believe these are the first such maps for over a century. Change was most pronounced and most consistent in those variables describing the onset of spring. Between 1971 and 2000, the thermal start of the growing season began on average 0.36 d yr–1 earlier and ended 0.10 d yr–1 later, suggesting an 11 d earlier beginning and 3 d later end of the growing season over the 30 yr period. For all but one of the temperature summaries, change has accelerated in recent time; however, change was not uniform across Europe.
%B Climate Research
%V 39
%P 191-207
%8 September 10, 20
%G eng
%U http://www.int-res.com/abstracts/cr/v39/n3/p191-207/
%0 Journal Article
%J Global Change Biology
%D 2006
%T Onset of spring starting earlier across the northern hemisphere
%A Mark D. Schwartz
%A Ahas, R.
%A Aasa, A.
%K climate change
%K phenology
%K spring
%X

Recent warming of Northern Hemisphere (NH) land is well documented and typically greater in winter/spring than other seasons. Physical environment responses to warming have been reported, but not details of large-area temperate growing season impacts, or consequences for ecosystems and agriculture. To date, hemispheric-scale measurements of biospheric changes have been confined to remote sensing. However, these studies did not provide detailed data needed for many investigations. Here, we show that a suite of modeled and derived measures (produced from daily maximum–minimum temperatures) linking plant development (phenology) with its basic climatic drivers provide a reliable and spatially extensive method for monitoring general impacts of global warming on the start of the growing season. Results are consistent with prior smaller area studies, confirming a nearly universal quicker onset of early spring warmth (spring indices (SI) first leaf date, −1.2 days decade−1), late spring warmth (SI first bloom date, −1.0 days decade−1; last spring day below 5°C, −1.4 days decade−1), and last spring freeze date (−1.5 days decade−1) across most temperate NH land regions over the 1955–2002 period.However, dynamics differ among major continental areas with North American first leaf and last freeze date changes displaying a complex spatial relationship. Europe presents a spatial pattern of change, with western continental areas showing last freeze dates getting earlier faster, some central areas having last freeze and first leaf dates progressing at about the same pace, while in portions of Northern and Eastern Europe first leaf dates are getting earlier faster than last freeze dates. Across East Asia last freeze dates are getting earlier faster than first leaf dates.